|The original problem (power light goes yellow instead of green, and computer will not bootup for at least an hour) sounds like an overheating fault. This might be cured by installing a case fan, inside the tower case (on a desktop or tower PC), or replacing a faulty CPU fan or faulty case fan.|
The power supply unit (PSU) is relatively unlikely to suffer from this sort of overheating fault, unless its internal fan has seized completely (which would be very obvious, since it is likely to simply result in a rapid PSU failure).
Sound is often controlled by a motherboard chip, so a sound fault might be related to the overheating problem. If it is not, however, read this page: http://www.annoyances.org/exec/foru...
Windows XP is a very large program (bloatware, IMHO) compared to Windows ME. A WinME system will struggle to run WinXP and will certainly run *very* slowly.